Customized patient-specific bone cutting blocks

ABSTRACT

A number of orthopaedic surgical instruments are disclosed. A method, apparatus, and system for fabricating such instruments are also disclosed.

This application is a national stage entry under 35 USC §371(b) ofInternational Application No. PCT/US2011/025892, filed Feb. 23, 2011,which claims priority under 35 U.S.C. §119(e) to U.S. Provisional PatentApplication Ser. No. 61/308,168, entitled “Customized Patient-SpecificBone Cutting Blocks,” which was filed on Feb. 25, 2010 by Luke Aram etal., and is a continuation-in-part application of co-pending U.S.Utility patent application Ser. No. 12/240,990 entitled “CustomizedPatient-Specific Instrumentation for Use In Orthopaedic SurgicalProcedures,” which was filed by Luke Aram et al. on Sep. 29, 2008, whichclaims priority under 35 U.S.C. §119(e) to U.S. Provisional PatentApplication Ser. No. 60/976,447 entitled “Method and Apparatus forFabricating Customized Patent Instrumentation,” which was filed on Sep.30, 2007 by Dan Auger et al.; U.S. Provisional Patent Application Ser.No. 60/976,448 entitled “Adjustable Customized Patient-SpecificOrthopaedic Surgical Instrumentation,” which was filed on Sep. 30, 2007by Luke Aram et al.; U.S. Provisional Patent Application Ser. No.60/976,451 entitled “Customized Patient-Specific Instrumentation For UseIn Orthopaedic Surgical Procedures,” which was filed on Sep. 30, 2007 byJeff Roose et al.; U.S. Provisional Patent Application Ser. No.60/976,444 entitled “Method and Apparatus for Patient-SpecificPositioning of Orthopaedic Surgical Instrumentation,” which was filed onSep. 30, 2007 by Luke Aram et al.; and U.S. Provisional PatentApplication Ser. No. 60/976,446 entitled “Method and Apparatus forAligning Customized Patient-Specific Orthopaedic Surgical Instruments,”which was filed on Sep. 30, 2007 by Luke Aram et al., each of theseapplications is assigned to the same assignee as the presentapplication, and each of which is hereby incorporated by reference.

CROSS-REFERENCE TO RELATED U.S. PATENT APPLICATIONS

Cross-reference is made to co-pending U.S. Utility patent applicationSer. Nos. 12/240,985; 12/240,990; 12/240,988; 12/240,992; 12/240,994;12/240,996; 12/240,997; 12/240,998; 12/241,006; 12/241,002; 12/241,001;and 12/240,999. Each of these applications was filed on Sep. 29, 2008,and is assigned to the same assignee as the present application. Each ofthese applications is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to customized patient-specificorthopaedic surgical instruments and to methods, devices, and systemsfor fabricating and positioning such instruments.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.A typical knee prosthesis includes a tibial tray, a femoral component, apolymer insert or bearing positioned between the tibial tray and thefemoral component, and, in some cases, a polymer patella button. Tofacilitate the replacement of the natural joint with the kneeprosthesis, orthopaedic surgeons use a variety of orthopaedic surgicalinstruments such as, for example, cutting blocks, drill guides, millingguides, and other surgical instruments. Typically, the orthopaedicsurgical instruments are generic with respect to the patient such thatthe same orthopaedic surgical instrument may be used on a number ofdifferent patients during similar orthopaedic surgical procedures.

SUMMARY

According to one aspect, a customized patient-specific femoral cuttingblock includes a body having a bone-facing surface that has a customizedpatient-specific negative contour configured to receive a portion of ananterior side of a patient's femur that has a corresponding positivecontour. The body also includes an outer surface that is opposite thebone-facing surface. The outer surface has a recessed area sized toreceive an end of a surgeon's finger. The recessed area corresponds to alocation on the body at which pressure is to be applied to couple thecustomized patient-specific femoral cutting block to the patient'sfemur. The customized patient-specific femoral cutting block alsoincludes at least one tab extending posteriorly from the body. The tabhas a bone-facing surface that includes a customized patient-specificnegative contour configured to receive a portion of the distal side ofthe patient's femur that has a corresponding positive contour.

The customized patient-specific femoral cutting block may include afirst tab extending posteriorly from the body and a second tab extendingposteriorly from the body. Each of such tabs may includes a customizedpatient-specific negative contour configured to receive a respectiveportion of the distal end of the patient's femur that has acorresponding positive contour. The first tab and the second tab maydefine an opening therebetween.

A first lip extends superiorly from an end of the first tab and a secondlip extends superiorly from an end of the second tab. Each of the firstlip and the second lip includes a customized patient-specific negativecontour configured to receive a respective portion of the posterior sideof the patient's femur that has a corresponding positive contour.

The body of the customized patient-specific femoral cutting block mayalso include a cutting slot defined therein. The cutting slot ispositioned to allow a surgeon to perform a distal cut on the patient'sfemur using the cutting slot.

A cutting guide may be coupled to the body of the customizedpatient-specific femoral cutting block. The cutting guide has a cuttingslot defined therein. The cutting guide is formed from a materialdifferent from the body and being positioned to allow a surgeon toperform a distal cut on the patient's femur using the cutting slot. Thecutting guide may be formed from a metallic material and overmolded tothe body of the customized patient-specific femoral cutting block.

The body of the customized patient-specific femoral cutting block has ananterior edge extending superiorly from an inferior surface. Therecessed area sized to receive an end of a surgeon's finger may beformed in the anterior edge of the body.

The body of the customized patient-specific femoral cutting blockincludes a cutting slot defined therein to allow a surgeon to perform adistal cut on the patient's femur using the cutting slot. The recessedarea sized to receive an end of a surgeon's finger is positionedinferiorly of the cutting slot.

The customized patient-specific femoral cutting block may also include alateral wing extending laterally from the body, and a medial wingextending medially from the body.

According to another aspect, a customized patient-specific tibialcutting block includes a body having a bone-facing surface that has acustomized patient-specific negative contour configured to receive aportion of an anterior side of a patient's tibia that has acorresponding positive contour. The body also includes an outer surfaceopposite the bone-facing surface. The outer surface has a recessed areasized to receive an end of a surgeon's finger. The recessed areacorresponding to a location on the body at which pressure is to beapplied to couple the customized patient-specific tibial cutting blockto the patient's tibia. The customized patient-specific tibial cuttingblock also includes at least one tab extending posteriorly from thebody. The tab has a bone-facing surface having a customizedpatient-specific negative contour configured to receive a portion of theproximal side of the patient's tibia that has a corresponding positivecontour.

The customized patient-specific femoral cutting block may include afirst tab extending posteriorly from the body and a second tab extendingposteriorly from the body. Each of such tabs may includes a customizedpatient-specific negative contour configured to receive a respectiveportion of the proximal end of the patient's tibia that has acorresponding positive contour. The first tab and the second tab maydefine an opening therebetween.

The body of the customized patient-specific tibial cutting block mayalso include a cutting slot defined therein. The cutting slot ispositioned to allow a surgeon to perform a cut on the patient's proximaltibia using the cutting slot.

A cutting guide may be coupled to the body of the customizedpatient-specific tibial cutting block. The cutting guide has a cuttingslot defined therein. The cutting guide is formed from a materialdifferent from the body and being positioned to allow a surgeon toperform a cut on the patient's proximal tibia using the cutting slot.The cutting guide may be formed from a metallic material and overmoldedto the body of the customized patient-specific femoral cutting block.

The body of the customized patient-specific tibial cutting block has ananterior edge. The recessed area sized to receive an end of a surgeon'sfinger may be formed in the anterior edge of the body.

The body of the customized patient-specific tibial cutting blockincludes a cutting slot defined therein to allow a surgeon to perform acut on the patient's proximal tibia using the cutting slot. The recessedarea sized to receive an end of a surgeon's finger is positionedsuperiorly of the cutting slot.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a simplified flow diagram of an algorithm for designing andfabricating a customized patient-specific orthopaedic surgicalinstrument;

FIG. 2 is a simplified flow diagram of a method for generating a modelof a patient-specific orthopaedic instrument;

FIG. 3 is a simplified flow diagram of a method for scaling a referencecontour;

FIGS. 4-6 are three-dimensional model's of a patient's tibia;

FIG. 7-9 are three-dimensional models of a patient's femur;

FIG. 10 is an anterior elevation an embodiment of a customizedpatient-specific orthopaedic surgical instrument;

FIG. 11 is a top plan view of the customized patient-specificorthopaedic surgical instrument of FIG. 10;

FIG. 12 is side elevation view of the customized patient-specificorthopaedic surgical instrument of FIG. 10;

FIG. 13 is an anterior elevation view of another embodiment of acustomized patient-specific orthopaedic surgical instrument;

FIG. 14 is a top plan view of the customized patient-specificorthopaedic surgical instrument of FIG. 13;

FIG. 15 is side elevation view of the customized patient-specificorthopaedic surgical instrument of FIG. 13;

FIG. 16 is a perspective view showing the customized patient-specificorthopaedic surgical instrument of FIG. 13 pinned to the femur of apatient;

FIG. 17 is an anterior elevation view of another embodiment of acustomized patient-specific orthopaedic surgical instrument;

FIG. 18 is a top plan view of the customized patient-specificorthopaedic surgical instrument of FIG. 17;

FIG. 19 is side elevation view of the customized patient-specificorthopaedic surgical instrument of FIG. 17; and

FIG. 20 is a perspective view showing a customized patient-specificorthopaedic surgical instrument that is substantially similar to thecustomized patient-specific orthopaedic surgical instrument of FIG. 17pinned to the tibia of a patient.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, et cetera, may be used throughoutthis disclosure in reference to the orthopaedic implants and instrumentsdescribed herein, along with a patient's natural anatomy. Such termshave well-understood meanings in both the study of anatomy and the fieldof orthopaedics. Use of such anatomical reference terms in thespecification and claims is intended to be consistent with theirwell-understood meanings unless noted otherwise.

Referring to FIG. 1, an algorithm 10 for fabricating a customizedpatient-specific orthopaedic surgical instrument is illustrated. What ismeant herein by the term “customized patient-specific orthopaedicsurgical instrument” is a surgical tool for use by a surgeon inperforming an orthopaedic surgical procedure that is intended, andconfigured, for use on a particular patient. As such, it should beappreciated that, as used herein, the term “customized patient-specificorthopaedic surgical instrument” is distinct from standard, non-patientspecific orthopaedic surgical instruments that are intended for use on avariety of different patients. Additionally, it should be appreciatedthat, as used herein, the term “customized patient-specific orthopaedicsurgical instrument” is distinct from orthopaedic prostheses, whetherpatient-specific or generic, which are surgically implanted in the bodyof the patient. Rather, customized patient-specific orthopaedic surgicalinstruments are used by an orthopaedic surgeon to assist in theimplantation of orthopaedic prostheses.

In some embodiments, the customized patient-specific orthopaedicsurgical instrument may be customized to the particular patient based onthe location at which the instrument is to be coupled to one or morebones of the patient, such as the femur and/or tibia. For example, insome embodiments, the customized patient-specific orthopaedic surgicalinstrument may include a bone-contacting or facing surface having anegative contour that matches or substantially matches the contour of aportion of the relevant bone of the patient. As such, the customizedpatient-specific orthopaedic surgical instrument is configured to becoupled to the bone of a patient in a unique location and position withrespect to the patient's bone. That is, the negative contour of thebone-contacting surface is configured to receive the matching contoursurface of the portion of the patient's bone. As such, the orthopaedicsurgeon's guesswork and/or intra-operative decision-making with respectto the placement of the orthopaedic surgical instrument are reduced. Forexample, the orthopaedic surgeon may not be required to locate landmarksof the patient's bone to facilitate the placement of the orthopaedicsurgical instrument, which typically requires some amount of estimationon part of the surgeon. Rather, the orthopaedic surgeon may simplycouple the customized patient-specific orthopaedic surgical instrumenton the bone or bones of the patient in the unique location. When socoupled, the cutting plane, drilling holes, milling holes, and/or otherguides are defined in the proper location relative to the bone andintended orthopaedic prosthesis. The customized patient-specificorthopaedic surgical instrument may be embodied as any type oforthopaedic surgical instrument such as, for example, a bone-cuttingblock, a drilling guide, a milling guide, or other type of orthopaedicsurgical instrument configured to be coupled to a bone of a patient.

As shown in FIG. 1, the algorithm 10 includes process steps 12 and 14,in which an orthopaedic surgeon performs pre-operative planning of theorthopaedic surgical procedure to be performed on a patient. The processsteps 12 and 14 may be performed in any order or contemporaneously witheach other. In process step 12, a number of medical images of therelevant bony anatomy or joint of the patient are generated. To do so,the orthopaedic surgeon or other healthcare provider may operate animaging system to generate the medical images. The medical images may beembodied as any number and type of medical images capable of being usedto generate a three-dimensional rendered model of the patient's bonyanatomy or relevant joint. For example, the medical images may beembodied as any number of computed tomography (CT) images, magneticresonance imaging (MRI) images, or other three-dimensional medicalimages. Additionally or alternatively, as discussed in more detail belowin regard to process step 18, the medical images may be embodied as anumber of X-ray images or other two-dimensional images from which athree-dimensional rendered model of the patient's relevant bony anatomymay be generated. Additionally, in some embodiments, the medical imagemay be enhanced with a contrast agent designed to highlight thecartilage surface of the patient's knee joint.

In process step 14, the orthopaedic surgeon may determine any additionalpre-operative constraint data. The constraint data may be based on theorthopaedic surgeon's preferences, preferences of the patient,anatomical aspects of the patient, guidelines established by thehealthcare facility, or the like. For example, the constraint data mayinclude the orthopaedic surgeon's preference for a metal-on-metalinterface, amount of inclination for implantation, the thickness of thebone to resect, size range of the orthopaedic implant, and/or the like.In some embodiments, the orthopaedic surgeon's preferences are saved asa surgeon's profile, which may used as a default constraint values forfurther surgical plans.

In process step 16, the medical images and the constraint data, if any,are transmitted or otherwise provided to an orthopaedic surgicalinstrument vendor or manufacturer. The medical images and the constraintdata may be transmitted to the vendor via electronic means such as anetwork or the like. After the vendor has received the medical imagesand the constraint data, the vendor processes the images in step 18. Theorthopaedic surgical instrument vendor or manufacturer process themedical images to facilitate the determination of the bone cuttingplanes, implant sizing, and fabrication of the customizedpatient-specific orthopaedic surgical instrument as discussed in moredetail below. For example, in process step 20 the vendor may convert orotherwise generate three-dimensional images from the medical images. Forexample, in embodiments wherein the medical images are embodied as anumber of two-dimensional images, the vendor may use a suitable computeralgorithm to generate one or more three-dimensional images form thenumber of two-dimensional images. Additionally, in some embodiments, themedical images may be generated based on an established standard such asthe Digital Imaging and Communications in Medicine (DICOM) standard. Insuch embodiments, an edge-detection, thresholding, watershead, orshape-matching algorithm may be used to convert or reconstruct images toa format acceptable in a computer aided design application or otherimage processing application. Further, in some embodiments, an algorithmmay be used to account for tissue such as cartilage not discernible inthe generated medical images. In such embodiments, any three-dimensionalmodel of the patient-specific instrument (see, e.g., process step 26below) may be modified according to such algorithm to increase the fitand function of the instrument.

In process step 22, the vendor may process the medical images, and/orthe converted/reconstructed images from process step 20, to determine anumber of aspects related to the bony anatomy of the patient such as theanatomical axis of the patient's bones, the mechanical axis of thepatient's bone, other axes and various landmarks, and/or other aspectsof the patient's bony anatomy. To do so, the vendor may use any suitablealgorithm to process the images.

In process step 24, the cutting planes of the patient's bone aredetermined. The planned cutting planes are determined based on the type,size, and position of the orthopaedic prosthesis to be used during theorthopaedic surgical procedure, on the process images such as specificlandmarks identified in the images, and on the constraint data suppliedby the orthopaedic surgeon in process steps 14 and 16. The type and/orsize of the orthopaedic prosthesis may be determined based on thepatient's anatomy and the constraint data. For example, the constraintdata may dictate the type, make, model, size, or other characteristic ofthe orthopaedic prosthesis. The selection of the orthopaedic prosthesismay also be modified based on the medical images such that anorthopaedic prosthesis that is usable with the bony anatomy of thepatient and that matches the constraint data or preferences of theorthopaedic surgeon is selected.

In addition to the type and size of the orthopaedic prosthesis, theplanned location and position of the orthopaedic prosthesis relative tothe patient's bony anatomy is determined. To do so, a digital templateof the selected orthopaedic prosthesis may be overlaid onto one or moreof the processed medical images. The vendor may use any suitablealgorithm to determine a recommended location and orientation of theorthopaedic prosthesis (i.e., the digital template) with respect to thepatient's bone based on the processed medical images (e.g., landmarks ofthe patient's bone defined in the images) and/or the constraint data.Additionally, any one or more other aspects of the patient's bonyanatomy may be used to determine the proper positioning of the digitaltemplate.

In some embodiments, the digital template along with surgical alignmentparameters may be presented to the orthopaedic surgeon for approval. Theapproval document may include the implant's rotation with respect tobony landmarks such as the femoral epicondyle, posterior condyles,sulcus groove (Whiteside's line), and the mechanical axis as defined bythe hip, knee, and/or ankle centers.

The planned cutting planes for the patient's bone(s) may then bedetermined based on the determined size, location, and orientation ofthe orthopaedic prosthesis. In addition, other aspects of the patient'sbony anatomy, as determined in process step 22, may be used to determineor adjust the planned cutting planes. For example, the determinedmechanical axis, landmarks, and/or other determined aspects of therelevant bones of the patient may be used to determine the plannedcutting planes.

In process step 26, a model of the customized patient-specificorthopaedic surgical instrument is generated. In some embodiments, themodel is embodied as a three-dimensional rendering of the customizedpatient-specific orthopaedic surgical instrument. In other embodiments,the model may be embodied as a mock-up or fast prototype of thecustomized patient-specific orthopaedic surgical instrument. Theparticular type of orthopaedic surgical instrument to be modeled andfabricated may be determined based on the orthopaedic surgical procedureto be performed, the constraint data, and/or the type of orthopaedicprosthesis to be implanted in the patient. As such, the customizedpatient-specific orthopaedic surgical instrument may be embodied as anytype of orthopaedic surgical instrument for use in the performance of anorthopaedic surgical procedure. For example, the orthopaedic surgicalinstrument may be embodied as a bone-cutting block, a drilling guide, amilling guide, and/or any other type of orthopaedic surgical tool orinstrument.

The particular shape of the customized patient-specific orthopaedicsurgical instrument is determined based on the planned location of theorthopaedic surgical instrument relative to the patient's bony anatomy.The location of the customized patient-specific orthopaedic surgicalinstrument with respect to the patient's bony anatomy is determinedbased on the type and determined location of the orthopaedic prosthesisto be used during the orthopaedic surgical procedure. That is, theplanned location of the customized patient-specific orthopaedic surgicalinstrument relative to the patient's bony anatomy may be selected basedon, in part, the planned cutting planes of the patient's bone(s) asdetermined in step 24. For example, in embodiments wherein thecustomized patient-specific orthopaedic surgical instrument is embodiedas a bone-cutting block, the location of the orthopaedic surgicalinstrument is selected such that the cutting guide of the bone-cuttingblock matches one or more of the planned cutting planes determined inprocess step 24. Additionally, the planned location of the orthopaedicsurgical instrument may be based on the identified landmarks of thepatient's bone identified in process step 22.

In some embodiments, the particular shape or configuration of thecustomized patient-specific orthopaedic surgical instrument may bedetermined based on the planned location of the instrument relative tothe patient's bony anatomy. That is, the customized patient-specificorthopaedic surgical instrument may include a bone-contacting surfacehaving a negative contour that matches the contour of a portion of thebony anatomy of the patient such that the orthopaedic surgicalinstrument may be coupled to the bony anatomy of the patient in a uniquelocation, which corresponds to the pre-planned location for theinstrument. When the orthopaedic surgical instrument is coupled to thepatient's bony anatomy in the unique location, one or more guides (e.g.,cutting or drilling guide) of the orthopaedic surgical instrument may bealigned to one or more of the bone cutting plane(s) as discussed above.

One illustrative embodiment of a method 40 for generating a model, suchas a computer model, of a patient-specific orthopaedic instrument isillustrated in FIGS. 2 through 9. The method 40 begins with a step 42 inwhich a cartilage thickness value is determined. The cartilage thicknessvalue is indicative of the average thickness of the cartilage of thepatient's bone. As such, in one embodiment, the cartilage thicknessvalue is equal to the average thickness of cartilage for an individualhaving similar characteristics as the patient. For example, thecartilage thickness value may be equal to the average thickness value ofindividuals of the same gender as the patient, the same age as thepatient, having the same activity level of the patient, and/or the like.In other embodiments, the cartilage thickness value is determined basedon one or more medical images of the patient's bone, such as thoseimages transmitted in process step 16.

In step 44, a reference contour of the patient's relevant bone isdetermined. The reference contour is based on the surface contour of athree-dimensional model of the patient's relevant bone, such as thethree-dimensional model generated in step 20. Initially the referencecontour is identical to a region (i.e. the region of interest such asthe distal end of the patient's femur or the proximal end of thepatient's tibia) of the patient's bone. That is, in some embodiments,the reference contour is juxtaposed on the surface contour of the regionof the patient's bone.

Subsequently, in step 46, the reference contour is scaled to compensatefor the cartilage thickness value determined in step 42. To do so, inone embodiment, the scale of the reference contour is increased based onthe cartilage thickness value. For example, the scale of the referencecontour may be increased by an amount equal to or determined from thecartilage thickness value. However, in other embodiments, the referencecontour may be scaled using other techniques designed to scale thereference contour to a size at which the reference contour iscompensated for the thickness of the cartilage on the patient's bone.

For example, in one particular embodiment, the reference contour isscaled by increasing the distance between a fixed reference point and apoint lying on, and defining in part, the reference contour. To do so,in one embodiment, a method 60 for scaling a reference contour asillustrated in FIG. 3 may be used. The method 60 begins with step 62 inwhich a medial/lateral line segment is established on thethree-dimensional model of the patient's relevant bone. Themedial/lateral line segment is defined or otherwise selected so as toextend from a point lying on the medial surface of the patient's bone toa point lying on lateral surface of the patient's bone. The medialsurface point and the lateral surface point may be selected so as todefine the substantially maximum local medial/lateral width of thepatient's bone in some embodiments.

In step 64, an anterior/posterior line segment is established on thethree-dimensional model of the patient's relevant bone. Theanterior/posterior line segment is defined or otherwise selected so asto extend from a point lying on the anterior surface of the patient'sbone to a point lying on posterior surface of the patient's bone. Theanterior surface point and the posterior surface point may be selectedso as to define the substantially maximum local anterior/posterior widthof the patient's bone in some embodiments.

The reference point from which the reference contour will be scaled isdefined in step 66 as the intersection point of the medial/lateral linesegment and anterior/posterior line segment. As such, it should beappreciated that the medial surface point, the lateral surface point,the anterior surface point, and the posterior surface point lie on thesame plane. After the reference point is initially established in step66, the reference point is moved or otherwise translated toward an endof the patient's bone. For example, in embodiments wherein the patient'sbone is embodied as a femur, the reference point is moved inferiorlytoward the distal end of the patient's femur. Conversely, in embodimentswhen the patient's bone is embodied as a tibia, the reference point ismoved superiorly toward the proximal end of the patient's tibia. In oneembodiment, the reference point is moved a distance equal to about halfthe length of the anterior/posterior line segment as determined in step64. However, in other embodiments, the reference point may be movedother distances sufficient to compensate the reference contour forthickness of the cartilage present on the patient's bone.

Once the location of the reference point has been determined in step 68,the distance between the reference point and each point lying on, anddefining in part, the reference contour is increased in step 70. To doso, in one particular embodiment, each point of the reference contour ismoved a distance away from the reference point based on a percentagevalue of the original distance defined between the reference point andthe particular point on the reference contour. For example, in oneembodiment, each point lying on, and defining in part, the referencecontour is moved away from the reference point in by a distance equal toa percentage value of the original distance between the reference pointand the particular point. In one embodiment, the percentage value is inthe range of about 5 percent to about thirty percent. In one particularembodiment, the percentage value is about ten percent.

Referring now to FIGS. 4-9, in another embodiment, the reference contouris scaled by manually selecting a local “high” point on the surfacecontour of the three-dimensional image of the patient's bone. Forexample, in embodiments wherein the relevant patient's bone is embodiedas a tibia as illustrated in FIGS. 4-6, the reference point 90 isinitially located on the tibial plateau high point of the tibial model92. Either side of the tibial plateau may be used. Once the referencepoint 90 is initially established on the tibial plateau high point, thereference point 90 is translated to the approximate center of theplateau as illustrated in FIG. 5 such that the Z-axis defining thereference point is parallel to the mechanical axis of the tibial model92. Subsequently, as illustrated in FIG. 6, the reference point is movedin the distal direction by a predetermined amount. In one particularembodiment, the reference point is moved is the distal direction byabout 20 millimeters, but other distances may be used in otherembodiments. For example, the distance over which the reference point ismoved may be based on the cartilage thickness value in some embodiments.

Conversely, in embodiments wherein the relevant patient's bone isembodied as a femur as illustrated in FIGS. 7-9, the reference point 90is initially located on the most distal point of the distal end of thefemoral model 94. Either condyle of the femoral model 94 may be used invarious embodiments. Once the reference point 90 is initiallyestablished on the most distal point, the reference point 90 istranslated to the approximate center of the distal end of the femoralmodel 94 as illustrated in FIG. 8 such that the Z-axis defining thereference point 90 is parallel to the mechanical axis of the femoralmodel 92. The anterior-posterior width 96 of the distal end of thefemoral model 94 is also determined. Subsequently, as illustrated inFIG. 9, the reference point is moved or otherwise translated in theproximal or superior direction by a distance 98. In one particularembodiment, the reference point is moved in the distal or superiordirection by a distance 98 equal to about half the distance 96. As such,it should be appreciated that one of a number of different techniquesmay be used to define the location of the reference point based on, forexample, the type of bone.

Referring now back to FIG. 2, once the reference contour has been scaledin step 46, the medial/lateral sides of the reference contour areadjusted in step 48. To do so, in one embodiment, the distance betweenthe reference point and each point lying on, and defining in part, themedial side and lateral side of the reference contour is decreased. Forexample, in some embodiments, the distance between the reference pointand the points on the medial and lateral sides of the scaled referencecontour are decreased to the original distance between such points. Assuch, it should be appreciated that the reference contour is offset orotherwise enlarged with respect to the anterior side of the patient'sbone and substantially matches or is otherwise not scaled with respectto the medial and lateral sides of the patient's bone.

The reference contour may also be adjusted in step 48 for areas of thepatient's bone having a reduced thickness of cartilage. Such areas ofreduced cartilage thickness may be determined based on the existence ofbone-on-bone contact as identified in a medical image, simulation, orthe like. Additionally, information indicative of such areas may beprovided by the orthopaedic surgeon based on his/her expertise. If oneor more areas of reduced cartilage thickness are identified, thereference contour corresponding to such areas of the patient's bone isreduced (i.e., scaled back or down).

Additionally, in some embodiments, one or more osteophytes on thepatient's bone may be identified; and the reference contour may becompensated for such presence of the osteophytes. By compensating forsuch osteophytes, the reference contour more closely matches the surfacecontour of the patient's bone. Further, in some embodiments, a distalend (in embodiments wherein the patient's bone is embodied as a tibia)or a proximal end (in embodiments wherein the patient's bone is embodiedas a femur) of the reference contour may be adjusted to increase theconformity of the reference contour to the surface contour of the bone.For example, in embodiments wherein the patient's bone is a femur, thesuperior end of the scaled reference contour may be reduced or otherwisemoved closer to the surface contour of the patient's femur in the regionlocated superiorly to a cartilage demarcation line defined on thepatient's femur. Conversely, in embodiments wherein the patient's boneis embodied as a tibia, an inferior end of the scaled reference contourmay be reduced or otherwise moved closer to the surface contour of thepatient's tibia in the region located inferiorly to a cartilagedemarcation line of the patient's tibia. As such, it should beappreciated that the scaled reference contour is initially enlarged tocompensate for the thickness of the patient's cartilage on the patient'sbone. Portions of the scaled reference contour are then reduced orotherwise moved back to original positions and/or toward the referencepoint in those areas where cartilage is lacking, reduced, or otherwisenot present.

Once the reference contour has been scaled and adjusted in steps 46 and48, the position of the cutting guide is defined in step 50. Inparticular, the position of the cutting guide is defined based on anangle defined between a mechanical axis of the patient's femur and amechanical axis of the patient's tibia. The angle may be determined byestablishing a line segment or ray originating from the proximal end ofthe patient's femur to the distal end of the patient's femur anddefining a second line segment or ray extending from the patient's anklethrough the proximal end of the patient's tibia. The angle defined bythese two line segments/rays is equal to the angle defined between themechanical axis of the patient's femur and tibia. The position of thebone cutting guide is then determined based on the angle between themechanical axes of the patient's femur and tibia. It should beappreciated that the position of the cutting guide defines the positionand orientation of the cutting plane of the customized patient-specificcutting block. Subsequently, in step 52, a negative contour of thecustomized patient-specific cutting block is defined based on the scaledand adjusted reference contour and the angle defined between themechanical axis of the femur and tibia.

Referring back to FIG. 1, after the model of the customizedpatient-specific orthopaedic surgical instrument has been generated inprocess step 26, the model is validated in process step 28. The modelmay be validated by, for example, analyzing the rendered model whilecoupled to the three-dimensional model of the patient's anatomy toverify the correlation of cutting guides and planes, drilling guides andplanned drill points, and/or the like. Additionally, the model may bevalidated by transmitting or otherwise providing the model generated instep 26 to the orthopaedic surgeon for review. For example, inembodiments wherein the model is a three-dimensional rendered model, themodel along with the three-dimensional images of the patient's relevantbone(s) may be transmitted to the surgeon for review. In embodimentswherein the model is a physical prototype, the model may be shipped tothe orthopaedic surgeon for validation.

After the model has been validated in process step 28, the customizedpatient-specific orthopaedic surgical instrument is fabricated inprocess step 30. The customized patient-specific orthopaedic surgicalinstrument may be fabricated using any suitable fabrication device andmethod. Additionally, the customized patient-specific orthopaedicinstrument may be formed from any suitable material such as a metallicmaterial, a plastic material, or combination thereof depending on, forexample, the intended use of the instrument. The fabricated customizedpatient-specific orthopaedic instrument is subsequently shipped orotherwise provided to the orthopaedic surgeon. The surgeon performs theorthopaedic surgical procedure in process step 32 using the customizedpatient-specific orthopaedic surgical instrument. As discussed above,because the orthopaedic surgeon does not need to determine the properlocation of the orthopaedic surgical instrument intra-operatively, whichtypically requires some amount of estimation on part of the surgeon, theguesswork and/or intra-operative decision-making on part of theorthopaedic surgeon is reduced.

Referring now to FIGS. 10-12, in one embodiment, the customizedpatient-specific orthopaedic surgical instrument may be embodied as afemoral cutting block 100. The cutting block 100 is configured to becoupled to the femur of a patient. The cutting block 100 includes a body102 configured to be coupled to the anterior side of the patient's femurand two arms or tabs 104, 106, which extend posteriorly away from thebody 102. The tabs 104, 106 are configured to wrap around a distal endof the femur as discussed in more detail below. Each of the tabs 104,106 includes an inwardly-curving or otherwise superiorly extending lip108, 110, respectively, which references the posterior condyles of thefemur. The cutting block 100 may be formed from any suitable material.For example, the cutting block 100 may be formed from a material such asa plastic or resin material. In some embodiments, the cutting block 100may be formed from a photo-curable or laser-curable resin. In oneparticular embodiment, the cutting block 100 is formed from a Veroresin, which is commercially available from Objet Geometries Ltd. ofRehovot, Israel using a rapid prototype fabrication process. However,the cutting block 100 may be formed from other materials in otherembodiments. For example, in another particular embodiment, the cuttingblock 100 is formed from a polyimide thermoplastic resin, such as aUltem resin, which is commercially available from Saudi Basic IndustriesCorporation Innovative Plastics of Riyhadh, Saudi Arabia.

The body 102 includes a bone-contacting or bone-facing surface 112 andan outer surface 114 opposite the bone-facing surface 112. The outersurface 114 includes a depression or recessed area 116, which providesan indication to a surgeon where to apply pressure to the body 102 whencoupling the cutting block 100 to the patient's femur. Additionally, anumber of guide pin holes or passageways 118 are defined through thebody 102 and have a diameter sized to receive respective guide pins tosecure the block 100 to the patient's femur. In some embodiments, one ormore of the guide pin holes 118 may be oblique or otherwise angled withrespect to the remaining guide pin holes 118 to further secure the block100 to the patient's bone.

The body 102 includes a modular cutting guide 120. That is, the body 102includes a cutting guide receiver slot 122 in which the cutting guide120 is received. A latch 124 or other locking device secures the cuttingguide 120 in place in the cutting guide receiver slot 122. As such, oneof a number of different cutting guides 120 having a cutting guide slot126 defined in various offset positions may be coupled to the body 102to allow a surgeon to selectively determine the amount of bone of thepatient's bone is removed during the bone cutting procedure. Forexample, a cutting guide 120 having a cutting guide slot 126 offset by+2 millimeters, with respect to a neutral reference cutting guide 120,may be used if the surgeon desires to remove a greater amount of thepatient's bone. The cutting guide 120 may be formed from the samematerial as the body 102 or from a different material. In one particularembodiment, the cutting guide 120 is formed form a metallic materialsuch as stainless steel.

The bone-facing surface 112 of the body 102 includes a negative contour128 configured to receive a portion of the anterior side of thepatient's femur having a corresponding contour. As discussed above, thecustomized patient-specific negative contour 128 of the bone-contactingsurface 112 allows the positioning of the cutting block 100 on thepatient's femur in a unique pre-determined location and orientation.

As discussed above, the arms or tabs 104, 106 extend posteriorly fromthe body 102 to define a U-shaped opening 105 therebetween. The tabs104, 106 may extend from the body 102 the same distance or a differentdistance. For example, as shown in FIG. 11, the tab 104 extends from thebody 102 a distance 130 and the tab 106 extends from the body 102 adistance 132, which is greater than the distance 130. Each of the tabs104, 106 includes a respective guide pin holes or passageways 138, 140defined therethrough. The guide pin holes 138, 140 have a diameter sizedto receive respective guide pin to further secure the block 100 to thepatient's femur.

The tabs 104, 106 include a bone-contacting or bone-facing surface 140,142, respectively, and an outer surface 144, 146, respectively, oppositethe bone-facing surface 140, 142. The bone-facing surface 140 of the tab104 includes a negative contour 148 configured to receive a portion ofthe distal side of the patient's femur having a respective correspondingcontour. Similarly, the bone-facing surface 142 of the tab 106 includesa negative contour 150 configured to receive a portion of the distalside of the patient's femur having a respective corresponding contour.

The lips 108, 110 of the tabs 104, 106 also include a bone-contacting orbone-facing surface 152, 154, respectively, and an outer surface 156,158, respectively, opposite the bone-facing surface 152, 154. Thebone-facing surface 152 of the lip 108 includes a negative contour 160configured to receive a portion of the posterior side of the patient'sfemur having a respective corresponding contour. Similarly, thebone-facing surface 154 of the lip 110 includes a negative contour 162configured to receive a portion of the distal side of the patient'sfemur having a respective corresponding contour. Each the lips 108, 110include a lateral slot 164 that forms a saw relief slot and isconfigured to provide an amount of clearance for the bone saw blade usedto remove a portion of the patient's bone. That is, during theperformance of the orthopaedic surgical procedure, a distal end of thebone saw blade may be received in the slot 164.

In some embodiments, the negative contours 128, 148, 150, 156, 158 ofthe bone-contacting surfaces 112, 140, 142, 152, 154 of the cuttingblock 100 may or may not match the corresponding contour surface of thepatient's bone. That is, as discussed above, the negative contours 128,148, 150, 156, 158 may be scaled or otherwise resized (e.g., enlarged)to compensate for the patient's cartilage or lack thereof.

In use, the femoral cutting block 100 is coupled to the distal end ofthe patient's femur. Again, because the bone-contacting surfaces 112,140, 142, 152, 154 of the cutting block 100 include the negativecontours 128, 148, 150, 156, 158, the block 100 may be coupled to thepatient's femur in a pre-planned, unique position. When so coupled, thetabs 104, 106 wrap around the distal end of the patient's femur and thelips 108, 110 of the tabs 104, 106 wrap around the posterior side of thepatient's femur. Additionally, when the block 100 is coupled to thepatient's femur, a portion of the anterior side of the femur is receivedin the negative contour 128 of the body 102, a portion of the distalside of the patient's femur is received in the negative contours 148,150 of the tabs 104, 106, and a portion of the posterior side of thefemur is received in the negative contours 156, 158 of the lips 108,110. As such, the anterior, distal, and posterior surfaces of thepatient femur are referenced by the femoral cutting block 100.

Referring now to FIGS. 13-16, in another embodiment, the customizedpatient-specific orthopaedic surgical instrument may be embodied as afemoral cutting block 200. The cutting block 200 is configured to becoupled to a femur of a patient similar to the cutting block 100described above. The cutting block 200 includes a body 202 configured tobe coupled to the anterior side of the patient's femur and two arms ortabs 204, 206, which extend posteriorly away from the body 202. The tabs204, 206 are configured to wrap around a distal end of the femur asdiscussed in more detail below. Each of the tabs 204, 206 includes aninwardly-curving or otherwise superiorly extending lip 208, 210,respectively, which references the posterior condyles of the femur.Similar to the cutting block 100, the cutting block 200 may be formedfrom any suitable material. For example, the cutting block 200 may beformed from a material such as a plastic or resin material. In oneparticular embodiment, the cutting block 200 is formed from Vero resinusing a rapid prototype fabrication process. However, the cutting block200 may be formed from other materials in other embodiments. Forexample, in another particular embodiment, the cutting block 200 isformed from a polyimide thermoplastic resin, such as a Ultem resin,which is commercially available from Saudi Basic Industries CorporationInnovative Plastics of Riyhadh, Saudi Arabia.

The body 202 includes a bone-contacting or bone-facing surface 212 andan outer surface 214 opposite the bone-facing surface 212. The outersurface 214 includes a number of guide holes or passageways 216 definedtherethrough. A guide pin bushing 218 is received in each guide hole216. The guide pin bushings 218 include an internal passageway 220 sizedto receive a respective guide pin to secure the block 200 to thepatient's femur. As shown in FIG. 15, the guide passageways 216 extendsfrom the outer surface 214 to the bone-facing surface 212 and iscounterbored on the bone-facing surface 212. That is, the passageway 216has an opening 222 on the bone-facing surface 212 having a diametergreater than the diameter of an opening 224 on the outer surface 214

The cutting block 200 includes a cutting guide 230 secured to the body202. In one particular embodiment, the cutting guide 230 is overmoldedto the body 202. The cutting guide 230 includes a cutting guide slot232. The cutting guide 230 may be formed from the same material as thebody 202 or from a different material. In one particular embodiment, thecutting guide 230 is formed from a metallic material such as stainlesssteel. The body 202 also includes a window or opening 234 definedtherethrough. The opening 234 allows a surgeon to visualize thepositioning of the block 200 on the patient's femur by viewing portionsof the femur through the opening 234. Additionally, the opening 234 mayreduce the amount of air pockets or other perfections created during thefabrication of the block 200. In the illustrative embodiment, theopening 234 extends from the cutting guide 200 to a point more superiorthan the superior-most point 236 of the guide pin bushings 218. However,in other embodiments, the cutting block 200 may include windows oropenings formed in the body 202 having other shapes and sizes.

Like the cutting block 100, the outer surface 214 of the cutting block200 includes a depression or recessed area 266 which provides anindication to a surgeon where to apply pressure to the body 202 whencoupling the cutting block 200 to the patient's femur. In theillustrative embodiment described herein, the recessed area 266 isformed as a generally arcuate-shaped recess formed in the anterior edge268 of the body 202 of the cutting block. As such, the recessed area 266is positioned inferiorly of the cutting slot 232. The recessed area 266is positioned on the body 202 at a location that correlates with a “highconfidence area” on the femur thereby providing an indication of thecorrect location for the surgeon to apply pressure on the cutting block200. In doing so, the recessed area 266 reduces, or even prevents,slippage of the surgeon's fingers or thumb which is particularly usefulsince the cutting block 200 is generally used in the presence of bodyfluids.

To further facilitate the surgeon's use of the cutting block 200, thebody 202 also includes a pair of wings 270. The medial and lateral wings270 are formed on opposite sides of the body 202 and extend outwardly inopposite directions away from the body's center. The wings 270 providean indication of the correct location for the surgeon to apply pressureon the cutting block 200.

The bone-facing surface 212 of the body 202 includes a negative contour238 configured to receive a portion of the anterior side of thepatient's femur having a corresponding contour. As discussed above, thecustomized patient-specific negative contour 238 of the bone-contactingsurface 212 allows the positioning of the cutting block 200 on thepatient's femur in a unique pre-determined location and orientation.

The tabs 204, 206 include a bone-contacting or bone-facing surface 240,242, respectively, and an outer surface 244, 246, respectively, oppositethe bone-facing surface 240, 242. The bone-facing surface 240 of the tab204 includes a negative contour 248 configured to receive a portion ofthe distal side of the patient's femur having a respective correspondingcontour. Similarly, the bone-facing surface 242 of the tab 206 includesa negative contour 250 configured to receive a portion of the distalside of the patient's femur having a respective corresponding contour.

As discussed above, the arms or tabs 204, 206 extend posteriorly fromthe body 202 to define a U-shaped opening 205 therebetween. The tabs204, 206 may extend from the body 202 the same distance or a differentdistance. For example, as shown in FIG. 14, the tab 204 extends from thebody 202 a distance 252 and the tab 206 extends from the body 202 adistance 254, which is less than the distance 252. Each of the tabs 204,206 includes a respective guide hole or passageway 260 definedtherethrough. A guide pin bushing 262 is received in each guide hole260. The guide pin bushings 262 include an internal passageway 264 sizedto receive a respective guide pin to further secure the block 200 to thepatient's femur. Similar to the guide passageways 216, the guidepassageways 260 may be counterbored on the bone-facing surface 240, 242of the tabs 204, 206.

The lips 208, 210 of the tabs 204, 206 also include a bone-contacting orbone-facing surface 272, 274, respectively, and an outer surface 276,278, respectively, opposite the bone-facing surface 272, 274. Thebone-facing surface 272 of the lip 208 includes a negative contour 280configured to receive a portion of the posterior side of the patient'sfemur having a respective corresponding contour. Similarly, thebone-facing surface 274 of the lip 210 includes a negative contour 282configured to receive a portion of the distal side of the patient'sfemur having a respective corresponding contour. Each the lips 208, 210include a lateral slot 284 that forms a saw relief slot and isconfigured to provide an amount of clearance for the bone saw blade usedto remove a portion of the patient's bone. That is, during theperformance of the orthopaedic surgical procedure, a distal end of thebone saw blade may be received in the slot 284.

In some embodiments, the negative contours 238, 248, 250, 280, 282 ofthe bone-contacting surfaces 212, 240, 242, 272, 274 of the cuttingblock 200 may or may not match the corresponding contour surface of thepatient's bone. That is, as discussed above, the negative contours 238,248, 250, 280, 282 may be scaled or otherwise resized (e.g., enlarged)to compensate for the patient's cartilage or lack thereof.

In use, the femoral cutting block 200 is coupled to the distal end ofthe patient's femur. Again, because the bone-contacting surfaces 212,240, 242, 272, 274 of the cutting block 200 include the negativecontours 238, 248, 250, 280, 282, the block 200 may be coupled to thepatient's femur in a pre-planned, unique position. When so coupled, thetabs 204, 206 wrap around the distal end of the patient's femur and thelips 208, 210 of the tabs 204, 206 wrap around the posterior side of thepatient's femur. Additionally, when the block 200 is coupled to thepatient's femur, a portion of the anterior side of the femur is receivedin the negative contour 238 of the body 202, a portion of the distalside of the patient's femur is received in the negative contours 248,250 of the tabs 204, 206, and a portion of the posterior side of thefemur is received in the negative contours 280, 282 of the lips 208,210. As such, the anterior, distal, and posterior surfaces of thepatient femur are referenced by the femoral cutting block 200.

Referring now to FIGS. 17-19, in another embodiment, the customizedpatient-specific orthopaedic surgical instrument may be embodied as atibial cutting block 300. The cutting block 300 is configured to becoupled to a tibia of a patient. The cutting block 300 includes a body302 configured to be coupled to the anterior side of the patient's tibiaand two arms or tabs 304, 306, which extend away from the body 302 in aposteriorly direction. The tabs 304, 306 are configured to wrap over aproximal end of the tibia as discussed in more detail below. The cuttingblock 300 may be formed from any suitable material. For example, thecutting block 300 may be formed from a material such as a plastic orresin material. In one particular embodiment, the cutting block 300 isformed from Vero resin using a rapid prototype fabrication process.However, the cutting block 300 may be formed from other materials inother embodiments. For example, in another particular embodiment, thecutting block 300 is formed from a polyimide thermoplastic resin, suchas a Ultem resin, which is commercially available from Saudi BasicIndustries Corporation Innovative Plastics of Riyhadh, Saudi Arabia.

The body 302 includes a bone-contacting or bone-facing surface 312 andan outer surface 314 opposite the bone-facing surface 312. The outersurface 314 includes a depression or recessed area 316, which providesan indication to a surgeon where to apply pressure to the body 302 whencoupling the cutting block 300 to the patient's tibia. Additionally, anumber of guide pin holes or passageways 318 are defined through thebody 302 and have a diameter sized to receive respective guide pins tosecure the block 300 to the patient's tibia. In some embodiments, one ormore of the guide pin holes 318 may be oblique or otherwise angled withrespect to the remaining guide pin holes 318 to further secure the block300 to the patient's bone.

The body 302 includes a modular cutting guide 320. That is, the body 302includes a cutting guide receiver slot 322 in which the cutting guide320 is received. A latch 324 or other locking device secures the cuttingguide 320 in place in the cutting guide receiver slot 322. As such, oneof a number of different cutting guides 320 having a cutting guide slot326 defined in various offset positions may be coupled to the body 302to allow a surgeon to selectively determine the amount of bone of thepatient's bone is removed during the bone cutting procedure. Forexample, a cutting guide 320 having a cutting guide slot 326 offset by+2 millimeters, with respect to a neutral reference cutting guide 320,may be used if the surgeon desires to remove a greater amount of thepatient's bone. The cutting guide 320 may be formed from the samematerial as the body 302 or from a different material. In one particularembodiment, the cutting guide 320 is formed form a metallic materialsuch as stainless steel.

The bone-facing surface 312 of the body 302 includes a negative contour328 configured to receive a portion of the anterior side of thepatient's tibia having a corresponding contour. As discussed above, thecustomized patient-specific negative contour 328 of the bone-contactingsurface 312 allows the positioning of the cutting block 300 on thepatient's tibia in a unique pre-determined location and orientation.

As discussed above, the arms or tabs 304, 306 extend posteriorly fromthe body 302 to define a U-shaped opening 305 therebetween. The tabs304, 306 may extend from the body 302 the same distance or a differentdistance. For example, as shown in FIG. 18, the tab 304 extends from thebody 302 a distance 330 and the tab 306 extends from the body 302 adistance 332, which is greater than the distance 330. The tabs 304, 306taper in the anterior-posterior direction. That is, the thickness of thetabs 304, 306 at an anterior end of the tabs 304, 306 is greater thanthe thickness of the tabs 304, 306 at a respective posterior end 307,309. The tapering of the tabs 304, 306 allows the tabs 304, 306 to beinserted within the joint gap defined between the patient's femur andtibia.

The tabs 304, 306 include a bone-contacting or bone-facing surface 340,342, respectively, and an outer surface 344, 346, respectively, oppositethe bone-facing surface 340, 342. The bone-facing surface 340 of the tab304 includes a negative contour 348 configured to receive a portion ofthe distal side of the patient's tibia having a respective correspondingcontour. Similarly, the bone-facing surface 342 of the tab 306 includesa negative contour 350 configured to receive a portion of the distalside of the patient's tibia having a respective corresponding contour.

In some embodiments, the negative contours 328, 348, 350 of thebone-contacting surfaces 312, 340, 342 of the cutting block 300 may ormay not match the corresponding contour surface of the patient's bone.That is, as discussed above, the negative contours 328, 348, 350 may bescaled or otherwise resized (e.g., enlarged) to compensate for thepatient's cartilage or lack thereof.

In use, the tibial cutting block 300 is coupled to the proximal end ofthe patient's tibia. Again, because the bone-contacting surfaces 312,340, 342 of the cutting block 300 include the negative contours 328,348, 350, the block 300 may be coupled to the patient's tibia in apre-planned, unique position. When so coupled, the tabs 304, 306 wraparound the proximal end of the patient's tibia. Additionally, when theblock 300 is coupled to the patient's tibia, a portion of the anteriorside of the tibia is received in the negative contour 328 of the body302 and a portion of the proximal side of the patient's tibia isreceived in the negative contours 348, 350 of the tabs 304, 306. Assuch, the anterior and proximal surfaces of the patient tibia arereferenced by the tibial cutting block 300.

Referring now to FIG. 20, there is shown another embodiment of thetibial cutting block 300. The tibial cutting block 300 of FIG. 20 issubstantially the same as the tibial cutting block of FIG. 17-19 exceptthat it does not include a modular cutting guide, but rather has a fixedcutting guide 320 overmolded into the polymer body 302.

Like the cutting block 300 shown in FIGS. 17-19, the tibial cuttingblock 300 of FIG. 20 includes a recessed area 316 that provides anindication to a surgeon where to apply pressure to the body 302 whencoupling the cutting block 300 to the patient's tibia. The recessed area316 is formed as a generally arcuate-shaped recess formed in thesuperior portion of the anterior edge 370 of the body 302 of the cuttingblock. As such, the recessed area 316 is positioned superiorly of thecutting slot 326. The recessed area 316 is positioned on the body 302 ata location that correlates with a “high confidence area” on the tibiathereby providing an indication of the correct location for the surgeonto apply pressure on the cutting block 300. In doing so, the recessedarea 316 reduces, or even prevents, slippage of the surgeon's fingers orthumb which is particularly useful since the cutting block 300 isgenerally used in the presence of body fluids. It should be appreciatedthat the recessed area 316 may also be embodied as a pair of recessedareas positioned on either side of the existing recessed are 316 (i.e.,located directly superior to the guide pin holes on the rounded superiorsurfaces where the tabs meet the body).

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the apparatus, system, and method describedherein. It will be noted that alternative embodiments of the apparatus,system, and method of the present disclosure may not include all of thefeatures described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the apparatus, system, andmethod that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

What is claimed is:
 1. A customized patient-specific femoral cuttingblock, comprising: a body having (i) a bone-facing surface that has acustomized patient-specific negative contour configured to receive aportion of an anterior side of a patient's femur that has acorresponding positive contour; (ii) an outer surface opposite thebone-facing surface, the outer surface having a recessed area sized toreceive an end of a surgeon's finger, the recessed area corresponding toa location on the body at which pressure is to be applied to couple thecustomized patient-specific femoral cutting block to the patient'sfemur, and at least one tab extending posteriorly from the body, the atleast one tab having a bone-facing surface having a customizedpatient-specific negative contour configured to receive a portion of thedistal side of the patient's femur that has a corresponding positivecontour; and (iii) a cutting guide coupled to the body, wherein: thecutting guide has a cutting slot defined therein, and the cutting guideis formed from a material different from the body and being positionedto allow a surgeon to perform a distal cut on the patient's femur usingthe cutting slot, wherein the cutting guide is formed from a metallicmaterial and is overmolded to the body of the customizedpatient-specific femoral cutting block.
 2. The customizedpatient-specific femoral cutting block of claim 1, wherein: the at leastone tab comprises a first tab extending posteriorly from the body and asecond tab extending posteriorly from the body, and each of the firsttab and the second tab includes a customized patient-specific negativecontour configured to receive a respective portion of the distal end ofthe patient's femur that has a corresponding positive contour, and thefirst tab and the second tab defining an opening therebetween.
 3. Thecustomized patient-specific femoral cutting block of claim 2, furthercomprising: a first lip extending superiorly from an end of the firsttab, and a second lip extending superiorly from an end of the secondtab, wherein each of the first lip and the second lip includes acustomized patient-specific negative contour configured to receive arespective portion of the posterior side of the patient's femur that hasa corresponding positive contour.
 4. The customized patient-specificfemoral cutting block of claim 1, wherein the body includes a cuttingslot defined therein, the cutting slot being positioned to allow asurgeon to perform a distal cut on the patient's femur using the cuttingslot.
 5. The customized patient-specific femoral cutting block of claim1, wherein: the body has an anterior edge extending superiorly from aninferior surface, and the recessed area sized to receive an end of asurgeon's finger is formed in the anterior edge of the body.
 6. Thecustomized patient-specific femoral cutting block of claim 1, wherein:the body includes a cutting slot defined therein to allow a surgeon toperform a distal cut on the patient's femur using the cutting slot, andthe recessed area sized to receive an end of a surgeon's finger ispositioned inferiorly of the cutting slot.
 7. The customizedpatient-specific femoral cutting block of claim 1, further comprising: alateral wing extending laterally from the body, and a medial wingextending medially from the body.